Trilobite facts for kids

Quick facts for kids Trilobites Temporal range: early Cambrian – late Permian
Asaphus kowalewskii
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Arachnomorpha
Class:	Trilobita

Trilobite ("three lobed") are extinct arthropods which were the first animals known to have eyes. They were very numerous during the early Palaeozoic era. Their distribution was worldwide, but only in salt water environments. They disappeared in the Permian–Triassic extinction event.

Trilobites had many lifestyles. Some moved over the sea floor as predators, scavengers, or filter feeders, Some swam, feeding on plankton. Most ecological niches of modern marine arthropods are seen in trilobites.

Their bodies were divided into three parts: the head (cephalon), the thorax (chest) made of up to 30 segments, and the tail (pygidium). Underneath, and rarely preserved, are three pairs of legs for the head. There are paired legs for each pleural groove.

Trilobites are the earliest known animal to have vision. The earliest trilobites had complex, compound eyes with lenses made of calcite. Some trilobites had small eyes or no eyes at all, and probably lived in dark environments.

Trilobites ranged in length from 1 millimetre (0.04 in) to 72 centimetres (28 in), with a typical size range of 3–10 cm (1.2–3.9 in). The world's largest trilobite, Isotelus rex, was found in 1998 by Canadian scientists on the shores of Hudson Bay.

Trilobites appeared some 600 million years ago during the Cambrian period. They belonged (probably) to the phylum Arthropoda. This phylum includes the most successful (78%) of all animal life forms, including crabs, centipedes, spiders, shrimps and insects. The trilobites, living in shallow seas, flourished as swimmers, crawlers and burrowers for some 350 million years. Over time, they evolved rapidly into a wide variety of strange and beautiful forms.

Discovery

They first captured man's eye some 25,000 years ago in France where two specimens were found in a Cro-magnon settlement, at a site called "La Grotte du Trilobite". One was found with a hole drilled into it and worn as an adornment. Others have been found in the tombs of Egypt, Greece and Rome. Trilobite fossils were sold on the street of 15th Century Europe and collected by Thomas Jefferson and Benjamin Franklin.

Images for kids

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  Redlichiida, such as this Paradoxides, may represent the ancestral trilobites

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  Walliserops trifurcatus, from Jebel Oufatene mountain near Fezzou, Morocco

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  Ogygopsis klotzi from the Mt. Stephen Trilobite Beds (Middle Cambrian) near Field, British Columbia, Canada

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  Cast of Isotelus rex, the largest-known trilobite, from the middle to upper Ordovician of North America

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  Cruziana, fossil trilobite-burrowing trace

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  Rusophycus, a "resting trace" of a trilobite; Ordovician of southern Ohio. Scale bar is 10 mm.

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  Illustration of the three types of hypostome. Doublure is shown in light gray, the inside surface of the cephalon in dark gray, and the hypostome in light blue. The glabella is outlined in red broken lines.

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  An enrolled phacopid trilobite Flexiclaymene meeki from the Upper Ordovician of Ohio

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  Koneprusia brutoni, an example of a species with elaborate spines from the Devonian Hamar Laghdad Formation, Alnif, Morocco

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  Life reconstruction of Triarthrus eatoni based on preserved soft body parts

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  Drawing of a biramous leg of Agnostus pisiformis

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  An exceptionally well preserved Olenoides serratus from the Burgess Shale. The antennae and legs are preserved as reflective carbon film.

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  The schizochroal eye of Erbenochile erbenii; the eye shade is unequivocal evidence that some trilobites were diurnal

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  Pitted fringes on the cephalon of the trinucleoidean Lloydolithus lloydi

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  Five Stages in the development of Sao hirsuta

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  Elrathia kingii growth series with holaspids ranging from 16.2 mm to 39.8 mm in length

See also

In Spanish: Trilobites para niños